+1 on leaving them as they are - you only really need to do it if you know that a particular service is eating your cpu, or misbehaving in some other way.
if you're not sure what you're doing, you could well get all sorts of nasty surprises - maybe not now, but in a few months time when you install a program and can't figure out why it's not working, and it's all due to having disabled service X and Y.
if you can't stop yourself tweaking though (i'm guilty of this
), then it's far safer to put services to 'manual' rather than 'disabled' - then they'll only run if needed.
you have been warned!